1. Field of the Invention
The present invention relates to an X-ray image sensor. More particularly, it relates to an X-ray image sensor having an excellent resistance to X-rays.
2. Description of the Related Art
An X-ray image sensor comprises a fiber optic faceplate, a phosphor screen for converting an X-ray image into a light image and an image sensing device such as a solidstate image and an image sensing device such as a solidstate image sensing device or a pick-up tube. The phosphor screen is formed on the X-ray incidence side of the fiber optic faceplate. The image sensing device is connected to the phosphor screen through the fiber optic faceplate.
In one example of the conventional X-ray image sensor,
the fiber optic faceplate is composed of flint glass optically bonded on the input side of the solid-state image sensing device and the phosphor screen is formed on the fiber optic faceplate.
In the conventional technique, X-rays are absorbed partly while being transmitted through the inside of the fiber optic faceplate, the fiber optic faceplate is browned by the X-rays and light generated in the phosphor screen is absorbed in the fiber optic faceplate, which results in deterioration of the detection sensitivity. Further, the X-rays transmitted through the fiber optic faceplate enter the solid-state image sensing device, which results in the increase of noise.